Fungi are
organisms that we
encounter in our
everyday lives..
..whether
know it or
you
not!
Very diverse
group of
organisms
Tremella mesenterica (Witches Butter)
Athlete’s Foot
Metatrichia vesparium (Slimemold)
1
Ring Worm
Geastrum tripex (Earthstar)
Roquefort or Blue
Cheese
Peltiger venosa
Various cultivated mushrooms
Camembert or Brie
Cheese
2
Leavened and Unleavened Bread
Rhizopus stolonifer (Zygospore)
Soy Products
Alcoholic Beverages
But
What is a Fungus?
Aseroe rubra (Stinkhorn)
3
A very
diverse
group of
organisms..
..genetically
and in
appearance
What is a Fungus?
1.Alexopolous (1952)
What is a
fungus?
"nucleated, achlorophyllous organisms
which typically reproduce sexually
and asexually, and whose usually
filamentous branched somatic
structures are surrounded by cell
walls"
Excluded slime molds!
What is a Fungus?
2.Alexopolous (1962)
"nucleated, achlorophyllous organisms
which typically reproduce sexually and
asexually, and whose usually
filamentous branched somatic
structures are surrounded by cell
walls"
composed of cellulose or chitin or
both
Included slime molds!
What is a Fungus?
3.Currently, in the sense of
most mycologists???
organisms that are nucleated,
achlorophyllous, typically reproduce
sexually and asexually by spores,
spores and
whose somatic structure is composed
of filamentous branched or yeast,
yeast
which are surrounded by cells walls
composed of chitin
Excludes slime molds and others!
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Characteristics of Fungi
1.Heterotrophs
a.Heterotroph categories:
i.Saprobes
ii.Parasites
iii.Facultative
Facultative saprobes and
parasites
Characteristics of Fungi
2.Fungus body
a.Hypha (pl.=Hyphae)
Mycelium (pl.=Mycelia)
b.Yeast
iv.Symbionts (mutulalistic)
Characteristics of Fungi
Characteristics of Fungi
2.Fungus body
a.Hypha (pl.=Hyphae)
Mycelium (pl.=Mycelia)
Mycelium forming circular colony
from radial growth (left) and
mycelium as observed with
microscope (right)
Coenocytic
Hypha
i.Coenocytic
ii.Septate
Septate Hypha
Septum
(pl.=septa)
Ô
Ô
Ñ
Mycelium
5
Characteristics of Fungi
Yeast
2.Fungus body
Ó
b.Yeast: unicellular, asexual
reproduction, budding or
fission.
c.Dimorphic: Having a yeast
and mycelium phase in the
same fungus.
Ñ
Rhodotorula:
Rhodotorula
Yeast
Mycelium
Tremella
mesenterica:
Dimorphic
3.Reproduce by spores
a.Variable in size, shape and
color. Sexual or asexual.
Budding Yeast
Spores are often borne directly
on modified hyphae
Spores are not always borne
directly on mycelium.
Penicillium notatum colony and
Fruitbodies, e.g. mushrooms
formed from mycelium produce
spores (sexual).
conidia and conidiophore (asexual)
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Fruiting Bodies can be of
various shapes, sizes and color
Characteristics of Fungi
4.Presence of cell wall: Chitin
and infrequently cellulose
5.Eukaryotes: Membrane bound
organelles, e.g. nuclei,
mitochondria, plasma
membrane, etc.
All are composed of tightly
interwoven mycelium.
Characteristics of Fungi
6.Mode of nutrition: Absorption
a. Fungi “live” in their food.
b. Digestive enzyme(s) released to
act on Insoluble food.
c. Break-down (digestion) of food.
d. Fungi “absorb
absorb” (=eat) digested
food.
e. Only sequence of events differ
from animal ingestion of food.
Summary of Absorption
Characteristics of Fungi
6.Mode of nutrition: Absorption
f. If food is soluble,
soluble e.g.,
composed of simple
molecules such as sugars and
amino acids, digestive
enzymes are not necessary.
g. Soluble food can be directly
absorbed into cells.
Sexual vs. Asexual
Reproduction
1.Sexual Reproduction
a. Two parents required.
b. Children borne will all be
genetically unique.
c. Children will inherit
characteristics from both
parents.
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Sexual vs. Asexual
Reproduction
2.Asexual Reproduction
a. Only one parent is involved.
b. Children borne will all be
genetically identical to
parent.
Post Scripts
World’s largest fairy rings:
Mushroom Armillaria gallica
reported on April 2,1992
1.Mycelium (rhizomorph
rhizomorph) of
mushroom covered 37 acres
Fairy ring is about 25 ft. in
diameter
World’s largest fairy rings:
Mushroom Armillaria ostoyae
reported on May 18,1992
1.Rhizomorphs of mushroom
covered 1500 acres
2.Age???
2.Over 1500 years old.
World’s largest fairy rings:
Mushroom Armillaria ostoyae.
1.Rhizomorph of mushroom
covered 2,200 acres
2.Over 2400 years old.
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Misconceptions About Fungi
1.Temperature: Fungi grow best
at warm temperatures
a. Probably most grow better
at 70-90°F., But…
b. Some can thrive at
temperatures of 130-150°F.
c. Some can thrive at temperatures
below 32°F (below freezing).
Misconceptions About Fungi
3.Light: Fungi grow best in the
dark.
a. Light is usually not important
in growth of fungi
b. Some species do have a light
requirement for reproduction,
but not for growth.
Misconceptions About Fungi
2.Water: Fungi need lots of
water.
a. Again, mostly true. But…
b. Some can grow in very dry
conditions, e.g. contaminate
grains and dried fruits.
c. Some can grow underwater.
Summary of Characteristics
1.Heterotrophs.
2.Body composed of hyphamycelium or yeast, or both.
3.Reproduce by spores
4.Cell Wall, usually of chitin,
rarely cellulose.
5.Eukaryotes
6.Mode of nutrition, absorption
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